linux-kernel - [v8 06/10] arm64: Always enable spectrev2 vulnerability detection

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Date:   Mon, 15 Apr 2019 16:21:25 -0500
From:   Jeremy Linton <jeremy.linton@....com>
To:     linux-arm-kernel@...ts.infradead.org
Cc:     catalin.marinas@....com, will.deacon@....com, marc.zyngier@....com,
        suzuki.poulose@....com, Dave.Martin@....com,
        shankerd@...eaurora.org, julien.thierry@....com,
        mlangsdo@...hat.com, stefan.wahren@...e.com,
        Andre.Przywara@....com, linux-kernel@...r.kernel.org,
        Jeremy Linton <jeremy.linton@....com>,
        Andre Przywara <andre.przywara@....com>
Subject: [v8 06/10] arm64: Always enable spectrev2 vulnerability detection

The sysfs patches need to display machine vulnerability
status regardless of kernel config. Prepare for that
by breaking out the vulnerability/mitigation detection
code from the logic which implements the mitigation.

Signed-off-by: Jeremy Linton <jeremy.linton@....com>
Reviewed-by: Andre Przywara <andre.przywara@....com>
Reviewed-by: Catalin Marinas <catalin.marinas@....com>
Tested-by: Stefan Wahren <stefan.wahren@...e.com>
---
 arch/arm64/kernel/cpu_errata.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
index 60cf87c4deb7..bd2cdd22da99 100644
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -109,7 +109,6 @@ cpu_enable_trap_ctr_access(const struct arm64_cpu_capabilities *__unused)
 
 atomic_t arm64_el2_vector_last_slot = ATOMIC_INIT(-1);
 
-#ifdef CONFIG_HARDEN_BRANCH_PREDICTOR
 #include <asm/mmu_context.h>
 #include <asm/cacheflush.h>
 
@@ -270,11 +269,11 @@ static int detect_harden_bp_fw(void)
 	    ((midr & MIDR_CPU_MODEL_MASK) == MIDR_QCOM_FALKOR_V1))
 		cb = qcom_link_stack_sanitization;
 
-	install_bp_hardening_cb(cb, smccc_start, smccc_end);
+	if (IS_ENABLED(CONFIG_HARDEN_BRANCH_PREDICTOR))
+		install_bp_hardening_cb(cb, smccc_start, smccc_end);
 
 	return 1;
 }
-#endif	/* CONFIG_HARDEN_BRANCH_PREDICTOR */
 
 #ifdef CONFIG_ARM64_SSBD
 DEFINE_PER_CPU_READ_MOSTLY(u64, arm64_ssbd_callback_required);
@@ -513,7 +512,6 @@ cpu_enable_cache_maint_trap(const struct arm64_cpu_capabilities *__unused)
 	.type = ARM64_CPUCAP_LOCAL_CPU_ERRATUM,			\
 	CAP_MIDR_RANGE_LIST(midr_list)
 
-#ifdef CONFIG_HARDEN_BRANCH_PREDICTOR
 /*
  * List of CPUs that do not need any Spectre-v2 mitigation at all.
  */
@@ -545,6 +543,11 @@ check_branch_predictor(const struct arm64_cpu_capabilities *entry, int scope)
 	if (!need_wa)
 		return false;
 
+	if (!IS_ENABLED(CONFIG_HARDEN_BRANCH_PREDICTOR)) {
+		pr_warn_once("spectrev2 mitigation disabled by configuration\n");
+		return false;
+	}
+
 	/* forced off */
 	if (__nospectre_v2) {
 		pr_info_once("spectrev2 mitigation disabled by command line option\n");
@@ -556,7 +559,6 @@ check_branch_predictor(const struct arm64_cpu_capabilities *entry, int scope)
 
 	return (need_wa > 0);
 }
-#endif
 
 #ifdef CONFIG_HARDEN_EL2_VECTORS
 
@@ -731,13 +733,11 @@ const struct arm64_cpu_capabilities arm64_errata[] = {
 		ERRATA_MIDR_ALL_VERSIONS(MIDR_CORTEX_A73),
 	},
 #endif
-#ifdef CONFIG_HARDEN_BRANCH_PREDICTOR
 	{
 		.capability = ARM64_HARDEN_BRANCH_PREDICTOR,
 		.type = ARM64_CPUCAP_LOCAL_CPU_ERRATUM,
 		.matches = check_branch_predictor,
 	},
-#endif
 #ifdef CONFIG_HARDEN_EL2_VECTORS
 	{
 		.desc = "EL2 vector hardening",
-- 
2.20.1